Reactions of Copper Flashcards
What is decanting?
Separates supernatant solution from solution by gently pouring the liquid without releasing any solid
What is a supernatant?
A clear liquid that remains on top of a solid or sediment
What is bumping?
The formation and subsequent bursting of large air bubbles trapped under a layer of solid precipitate in solution
What is filtrate?
Leftover solution from a reaction
What is coagulation?
When particles in a precipitate bunch up together (simplistically)
What occurs in the first reaction of copper?
Copper wire is sanded, weighed, curled up, and then dissolved with concentrated nitric acid. The beaker is swirled to remove brown trapped air from the green solution, producing a blue copper (II) nitrate solution.
What occurs to the copper (II) nitrate solution?
Solution is diluted with DI water (poured quickly) and then NaOH is slowly added to the diluted Cu(NO3)2 solution. Paper should be strongly alkaline (pH > 10).
What is the third step of the copper experiment?
Gelatinous copper (II) hydroxide mixture decomposes due to heat applied by a bunsen burner, producing solid black CuO. The copper oxide will then undergo vacuum filtration. Filtrate will be discarded.
(the beaker must be rinsed at least three times to ensure all precipitate is present on the filter paper)
Why did copper (II) hydroxide have to be turned into copper oxide?
It is because its separation by filtration proceeds slowly and is ineffective
What is quantitative transfer?
Simply means that all the material you are investigating must be
moved from one place to another, without any loss of sample
What occurs to the solid CuO?
Sulphuric acid is added to the copper oxide in the beaker and stuck precipitate that may be on the filter paper. Swirl until completely dissolved into copper (II) sulphate.
Why is sulphuric acid added?
Because copper (II) sulphate is water-soluble and dissolves as it is formed from CuO. Copper ions are hydrated and then converted to Cu because of the high solubility of copper sulphate.
What occurs to the copper (II) sulphate solution?
Zinc metal is weighed and added in proportions to the blue copper (II) sulphate solution (ensure that a snorkel exhaust is used). Swirl until blue colour disappears. This produces solid copper and zinc sulphate (which is very soluble).
Zn is ______ and HCl is _____ during the redox reaction reaction
1) oxidized
2) reduced
How the excess zinc removed?
HCl is added to the solution (with continuous swirling) to dissolve excess zinc. Isolate the solid copper by decanting the supernatant solution (with two rinses of DI water). The wet precipitate is then transfered to an evaporation dish and heated up with a bunsen burner (cool flame) until dry.
Name 4/5 common errors in this experiment
- Using the wrong flash
- Loss of product from decanting
- Loss of product from filtration
- Using the wrong acid
- Not stiring during the heating of copper (II) hydroxide
